Carl Haub

(February 2001) The United Nations Population Division today released the latest in its eagerly awaited biennial global population projections. World Population Prospects, the 2000 Revision, projects a population of 9.3 billion in the year 2050 in its medium variant, up from 8.9 billion in the 1998 edition.

The UN projections are widely used throughout the UN system and by researchers everywhere and are the most comprehensive projection series available, offering estimates and projections for the world's countries from 1950 to 2050. The full report, offering a wide variety of demographic variables, is expected in mid-2001.

The 2000 edition paints a picture for the 21st century that is in many ways different from that of the 20th century. The 20th century saw an explosion of population growth in the less developed countries, while much of the more developed world grappled with economic crises and the devastation of wars, which often resulted in low birth rates. By the end of the 20th century, economics and changing lifestyles in many of the more developed countries had dropped births to unbelievably low levels (as low as only 1.1 children per couple).

World Population: How Large by Mid-Century?

Source: United Nations, World Population Prospects: The 2000 Revision Highlights (2001).

The less developed countries, whose rapidly rising life expectancy after World War II was the root of the well-known population "explosion," ended the century with a mix of demographic situations. Some countries had reacted quickly to growth rates reaching unheard-of levels — enough to double populations in 20 years or less — and achieved varying degrees of success in lowering births to curb population growth. For other countries, the reaction came later and, as a result, their growth rates remain higher. The ultimate size of world population is highly dependent upon whether family size reaches the key two-child-per-couple level, enough to ultimately stabilize population growth.

The other key issue for the new century is AIDS. HIV/AIDS prevalence levels in many countries have risen to catastrophic levels, particularly in sub-Saharan Africa. Previously, demographers routinely assumed gradually rising life expectancy and improved health conditions in all countries, an assumption generally backed by the actual trends. AIDS has changed all that and, for the first time in the history of modern population projections, rising mortality levels caused by an intractable disease has become a key element of projections.

AIDS Is Slashing Years off Life Expectancy

Source: United Nations, World Population Prospects: The 2000 Revision Highlights (2001).

Here are some highlights from the UN executive summary issued on Feb. 28:

Global population in 2050 is expected to fall within a range of 7.9 billion to 10.9 billion, up from 6.1 billion today. The medium variant projection of 9.3 billion is the one most often used as a reasonable, "middle of the road" expectation of future growth by 2050.

All of the projected world population growth is expected to be in the less developed countries of Africa, Asia, Latin America, and Oceania. As a group, the more developed countries (North America, Europe, Australia, Japan, and New Zealand) are projected to remain nearly the same size by 2050 in the medium variant. In fact, the populations of 39 more developed countries are expected to shrink by 2050, because of historically low levels of fertility. Significant population growth is anticipated, however, for several more developed countries, such as Australia, New Zealand, and the United States. But this growth will be offset by losses in other more developed countries.

The higher global population in 2050 is a result of several factors. Higher birth rate estimates than in previous projections are now used, most notably in Bangladesh, India, and Nigeria. In addition, these higher birth rates are expected to continue for a longer period.

The population of the less developed countries is expected to grow from 4.9 billion in 2000 to 8.1 billion (medium variant), while that of the more developed countries remains essentially stable, varying from 1.1 billion to 1.3 billion. More developed countries' share of world population will shift from Europe to non-European countries, particularly the United States.

The devastating impact of the HIV/AIDS pandemic is even more apparent in these newly revised projections. For example, the population of Kenya (31 million) is projected to be 26 percent less, or almost 20 million less in 2050 than it would have been without AIDS. Other countries with similar outlooks are Botswana (43 percent less), Burundi (22 percent less), Guyana (19 percent less), Lesotho (44 percent less), Malawi (24 percent less), Mozambique (22 percent less), Namibia (25 percent less), South Africa (39 percent less), Swaziland (38 percent less), Zambia (22 percent less), and Zimbabwe (33 percent less). Surprisingly, all of these countries are projected to have a larger population size in 2050 than at present, a result of current high birth rates.

Worldwide, and particularly in the more developed countries, the number of people ages 60 and over will more than triple, rising from 606 million in 2000 to 2 billion by 2050. The "oldest old," those 80 and over, will increase more than fivefold, from 69 million in 2000 to 379 million in 2050.